The biggest new rock act in the world doesn’t play indie or metal, and it doesn’t have anything to do with Jack White or the Black Keys (at least not yet). Actually, it’s a boy band. Australian quartet 5 Seconds of Summer blew up last year with “She Looks So Perfect,” which features the indelible chorus “She looks so perfect standing there/In my American Apparel underwear.” 5SOS got their start opening for One Direction, whom they rival in catchiness and cuteness, but their music is powered by a completely different strain of hormonal napalm. They play guitars, write a decent chunk of their music and work a pop-punk sound that evokes Blink-182 more than the Backstreet Boys.

The band formed in 2011 at a Christian high school near Sydney, where it got noticed posting YouTube covers and were soon scooped up and lofted into the Top 40. 5SOS’ 2014 debut cranked out neon-lime Green Day tuneage with a light spritz of suburban emo ennui — as if every song was expressly designed to soundtrack a graduation party montage in an American Pie movie.

Their second LP shows off their musical knowledge and ambition without getting in the way of their own preternatural adorableness. “Hey Everybody!” comes litigiously close to the melody from Duran Duran’s “Hungry Like the Wolf”; “Permanent Vacation” features singer Michael Clifford’s best Billie Joe Armstrong impression as he fires off complaints about corporations “taking over the radio stations,” which feels especially ballsy coming from a band whose biggest song is basically an ad for a clothing brand. The boffo power-ballad moment is “Jet Black Heart,” where Clifford ties a scary emotional weather report (“I’ve got a jet-black heart, and there’s a hurricane underneath it”) to a melody so obvious, Hodor from Game of Thrones could jump in on the chorus.

These guys have more teenage girls in their audience than any punkish band ever, which means that they can’t make like far-too-many punkish bands before them and treat the opposite gender like a race of icky space aliens. There’s real generosity in “San Francisco,” a strummy gusher about a hookup that might turn into something more. The only time they break this rule is, sadly, with their hit “She’s Kinda Hot,” where singer Luke Hemmings whine-snarls about a smokin’ girlfriend (sick!) who’s a bit of a nag (lame!). It kind of makes you want to grab the whole band and drown it in the tub. But that’s a rare moment. Usually, these boys have more guts than some bands twice their age.